The present invention relates generally to brine saturator tanks used in conjunction with electrolytic cells. More particularly, the invention relates to the liquid level indicator apparatus used in such brine saturators to indicate the level of liquid within the brine saturator tank.
Commercial cells for the production of chlorine and alkali metal hydroxides have been continually used and developed from about 1892 to the present. Regardless of the type of cells employed in this production, the process requires the use of a saturated brine solution. Generally depleted brine is removed from the chlor-alkali cells and replenished in a brine saturator tank by the addition of fresh water and rock salt. The salt, fresh water and depleted brine is allowed to mix together to form a slurry.
Naturally, the entire electrolytic process is dependent upon having a sufficient amount of saturated brine to be electrolyzed within the cells. Thus, devices have been designed to monitor the liquid or brine solution level in the saturator tanks. However, the liquid level monitoring or indicating devices have proven susceptible to plugging from insolubles such as lime, sand, and salt particles, found in the solution. Since the rock salt normally is added directly into the top of the tank or saturator vessels, there has also been a problem with the brine or liquid level sensing apparatus breaking from the weight of the rock salt which is normally gravity fed on top of the apparatus in the saturator vessel.
Should the level indicator apparatus plug with insolubles or break, the level of the fluid in the saturator will not accurately be reflected. This could cause the liquid level in the saturator vessel to become too low or even be exhausted. This would obviously affect the operation of the electrolytic cells serviced by the saturator vessel. Should the level of saturated brine drop too low, the pumps circulating it through the brine system to the cells could cavitate and cause the entire system to be depleted of brine. In such instances, the entire bank of electrolytic cells fed brine from the affected brine saturator tank or vessel must be shutdown until there is sufficient pressure built up again in the pumps to recommence operation. At a minimum, this can take several hours since it is necessary to refill the slurry vessel with make up water. If the level indicator apparatus is plugged or broken, it can take several days to clear away the built up pile of rock salt that may cover the apparatus and to unplug or repair the apparatus. On the other extreme, the plugging of the level indicator apparatus could call for the addition of excessive amounts of fresh water by an automatic water make up system to respond to an erroneously low indication of liquid. This could lead to flooding of the slurry vessel and the general cell area.
These problems are solved in the design of the present invention which provides an improved liquid level indicator apparatus which may be utilized in any type of electrolytic cell requiring a salt for electrolysis.